94 Sierra Help

chickensoup · July 18, 2009

whats up guys just picked up a high milage 94 sierra z71 ext cab. there appears to be a short somewhere in the system. the windshield wipers are running at random times and anytime i turn an acc on (lights,ac) anyone else heard of this? also where the water temp sending unit at? its a 350

bill190 · July 19, 2009

The coolant temperature sender (for the dash temperature gauge) should be on the side of the engine near the 1st cylinder.

There is also a coolant temperature "sensor" for the engine computer which is usually up by the radiator hose.

As to the wiper problem, check for bare wires and do-it-yourself add-on's tapped into the wiper wires.

Other than that, you could guess and replace the wiper switch.

Or find the trouble for sure by using a multimeter and a GM Factory Service Manual set which would have a complete wiring diagram. Order that from helminc.com

chickensoup · July 19, 2009

The coolant temperature sender (for the dash temperature gauge) should be on the side of the engine near the 1st cylinder.

There is also a coolant temperature "sensor" for the engine computer which is usually up by the radiator hose.

As to the wiper problem, check for bare wires and do-it-yourself add-on's tapped into the wiper wires.

Other than that, you could guess and replace the wiper switch.

Or find the trouble for sure by using a multimeter and a GM Factory Service Manual set which would have a complete wiring diagram. Order that from helminc.com

as far as electrical here are my symtoms,when i turn my headlights on my wipers come on when i hit the brakes or brights and sometimes turn signals the wipers run with them. if i hold the brake and use my turn signal the oposite turn signal blinks dimly along with the one iam using which lights up normal. when i try to run the radio it loses power if i hit brakes,headlights anything like that.when i try to use the a/c with anything else it feels like its gonna stall. the whole time iam geting volt reading of just above 9 at idle and maybe 10 at speed.all my gauges fluctuate.had the battery and alt tested and they checked out fine.

bill190 · July 19, 2009

Well you have a serious charging system problem!

When you turn the ignition switch on (don't start), the battery should measure 12 something volts.

After starting the vehicle, the battery should measure 13/14 volts. This is the alternator kicking in and charging the battery.

If the alternator is not working or there is a problem with the wiring going from the battery to the alternator, the battery will slowly die.

12 volts...

11 volts...

10

9

8

etc.

You can stick a plug-in battery charger on your battery and it will charge back up!

8

9

10

11

12

The alternator in a vehicle should keep it charged.

Electronic things in newer vehicles do not work under around 9 volts. Charge your battery with a plug in charger and I bet everything starts working again.

If you have to keep charging your battery, there is a problem with your charging system!

Complete troubleshooting instructions for this would be in a GM factory service manual set for your year/model vehicle - order from helminc.com or a GM dealer. Some of this would be covered in books sold at auto parts stores, but these tend to cover many different models and years, so can be confusing if they talk about a part your vehicle does not have.

chickensoup · July 19, 2009

ok i took the dash and windshield wipers apart as much as i could and cleaned everything with electrical cleaner and compressed air. now my volts and everything are good but my windshield wipers are still acting crazy,

bill190 · July 19, 2009

ok i took the dash and windshield wipers apart as much as i could and cleaned everything with electrical cleaner and compressed air. now my volts and everything are good but my windshield wipers are still acting crazy,

You're going to need a wiring diagram for that. Then test with a multimeter that it is getting good power, then test various points in the circuit to find the problem.

Haynes has a book on automotive electrical troubleshooting which might be helpful so far as learning to do electrical troubleshooting. They may have this or something similar in your local auto parts store. But you still need a wiring diagram to see how this works.

If you can disconnect just the switches, that might be a good start. See if the wipers still activate with the switches disconnected. Isolate the problem!

Book: Automotive Electrical Manual - All Common Repairs (Haynes)

http://www.themotorbookstore.com/el.html

grose67 · July 20, 2009

Sounds like you may have a hot wire that is grounding out somewhere. I had a 79 Chevy that almost drove me nuts until I figured it out.

chickensoup · July 20, 2009

yeah i got the haynes just wondering if anyone had a similar problem.gonna go between all the fuses with a test light tommorow. any other tricks to make finding it quicker?

thanks for all the replies:)

bill190 · July 20, 2009

A multimeter for testing would be better.

With a switch...

There is "off". (normal new switch)

There is "on". (normal new switch)

There is "almost off" (malfunctioning older switch)

There is "almost on" (malfunctioning older switch)

There is "in-between off and on" (malfunctioning older switch)

There is short to - (ground).

There is short to + (positive)

(Of either wire connected to a switch)

Then with the power to something like a wiper, there is 12 volts, then when the unit is switched on, it could be 12 volts, or it could be 8 or 9 volts with a load (poor connection somewhere). And it may work fine with a good connection and 12 volts, but do crazy things at 9 volts or less! Fix the poor connection, get 12 volts with it on, and it works like new!

With a multimeter, you can test for ohms on the switch or wires and tell just how good of a connection it is. Or test the voltage and see how good the power is. Or test for voltage for a short to +. Or test with ohms for a short to ground. Or test that a switch is entirely off as it should be when off.

But need to do a bit of reading to learn how to use a multimeter first. Basically learn about the ohm meter and volt meter portions of the multimeter for automotive work.

An example of a problem...

There is a wiper switch which has electrical contacts inside of it. There is dust and dirt which has been blown into the switch. This dust and dirt is "slightly" shorting several of the electrical contacts together. Almost enough of a connection to make the wiper go, but not quite. Add a bit of humidity and the wiper goes on its own.

To test the above, I would look at a wiring diagram and see if there was a connector to the wiper switches I could disconnect to test them. Then see what colored wires went to what. Let's keep it simple and say red is power, blue is for the wiper, and green is for the washer.

So I would disconnect the connector to the switches.

Then be sure the wiper and washer switch was off.

Then measure with an ohm meter between each with the ohm meter set on high ohms. There should be NO connection between any of the wires in this hypothetical case.

But I see there is a connection between red and blue. I lower the ohms scale on my multimeter to the lowest I can and still get a reading. I see it is a 100 ohm short between the two wires. It should be 0 ohms at the highest scale when the switch is off! There is a problem with the switch! (Just dirt between the two contacts making "partial" contact between the two. Not off. Not on. In-between!

Also none of the 3 wires should have a connection to ground. (Looking at my hypothetical wiring diagram.) I can place the ohm meter on high ohms and check each wire to the metal on the steering column for a short to ground.

I can also place the multimeter on DC volts low scale and check each wire for a voltage to +. (Learn when to use ohms and when to use voltage when learning how to use a multimeter.)

And I can check for low ohms between the red and blue wire, then turn on the wiper switch and see how good of a connection it is. I would want close to 0 ohms on the low scale.

And I could do the same with the red and green and turn on the washer switch.

Note: The above has NOTHING to do with any real wiper switch. Some switch + to go to the wiper/washer. Some switch - to go to the wiper washer. Need to look at the wiring diagram for the specific vehicle to see how it works. I've seen the same vehicle manufacturer switch from a + switching scheme one year, to - the next, then back to + a few years later!

How to use a multimeter...

http://www.google.com/search?hl=en&saf...ter&aqi=g10

REV353 · July 20, 2009

I had a bad ground connection in the left front around the headlight, I had to take the grill off to clean it. I am not sure how,what or why but that was my problem when my truck did that.

chickensoup · July 20, 2009

well i did a check on the fuse box with all doors shut and lights,ign etc. off.

the ctsy,park lps and stop fuse were all hot wether the ign was on or off.

also the pnl lps isnt geting power at all even with the ign on. fuses are all ok.

also do u know if the gauges out of a chevy same model and year will work in my gmc? the only differeance i see is it has a tach which i know obviously wont work.

grose67 · July 21, 2009

well i did a check on the fuse box with all doors shut and lights,ign etc. off.
the ctsy,park lps and stop fuse were all hot wether the ign was on or off.

also the pnl lps isnt geting power at all even with the ign on. fuses are all ok.

also do u know if the gauges out of a chevy same model and year will work in my gmc? the only differeance i see is it has a tach which i know obviously wont work.

Dont think it will help your situation.

chickensoup · July 21, 2009

^ err yeah i know......i got a bad water gauge too.

chickensoup · July 24, 2009

UPDATE well i took er for a long ride yesterday and she threw a code 81 at me (2/3 shift solonoid short or open) so ive found my circuit.

ive also noticed a very small oil leak coming from the housing where the oil filter and oil cooler lines go in iam assuming theres an o ring i there.

thanx to everyones who's responded to this thread iam gonna have to post some pics. rest assure this is no jalopy your trying to help me save its a true classic.

grose67 · July 24, 2009

Allways glad to help if I can. I have a 98 and an appreciation for the older trucks.Glad it finally threw a code. That could save hours of head banging the wall frustration. Let us know if that clears up the problem.